Effects Of Exogenous Application Of MG And H₂S On Antioxidant System Activity And Resistance Gene Expression In Salix Matsudana Koidz Under Cadium Exposure

The problem of heavy metal cadmium pollution is becoming more and more serious.Excessive cadmium in soil not only affect the growth of plants,but also ultimately affect human health through the food chain.In order to study the response of physiological and related gene expression of exogenous application of methylglyoxal?MG?and hydrogen sulfide?H₂S?donor sodium hydrosulfide?NaHS?under the stress of cadmium?Cd?,the experiment set CK,150 mg·kg^-1Cd,1.5 mmol·kg^-11 MG,Cd+MG,50 mg·kg^-11 NaHS,Cd+NaHS,MG+NaHS,Cd+MG+NaHS eight treatment groups,samples were collected After treated 20d and 40d respectively,and the plant height of Salix matsudana Koidz was determined.The leaf area and the Cd content of the roots and leaves of Salix matsudana Koidz on the 40th day as well as the hydrogen peroxide?H₂O₂?content and the superoxide radical(O₂^.-)production rate in the leaves of Salix matsudana were determined;catalase?CAT?,superoxide dismutase?SOD?,ascorbate peroxidase?APX?,glutathione reductase?GR?,monodehydroascorbate oxidase?DHAR?,dehydroascorbate oxidase?MDHAR?activity,vulcanization the contents of hydrogen?H₂S?,malondialdehyde?MDA?and proline?Pro?were also determined.The expression of antioxidant enzymes?SOD,CAT,APX,GR?and phytochelatin synthase?PCS?,ABC transporter type B?ABCB?,metallothionein in leaves of Salix matsudana were also determined.The results show that:Under Cd stress,the plant height and leaf area increment of Salix matsudana Koidz were significantly inhibited,while the application of NaHS and MG by Cd stress reduced the plant height and leaf area increment of Salix matsudana Koidz to the control level.Under cadmium stress.Root accumulate highest concentration of Cd and followed by leaf and stem.Exogenous application of MG and NaHS under cadmium stress reduced the uptake of cadmium by root cells and alleviate the toxic effect of cadmium on Salix matsudana Koidz.The production rate of H₂O₂ content and O₂^.-under cadmium stress were significantly higher than control,while the ROS level was significantly decreased after application of MG and NaHS under cadmium exposure.Under the condition of Cd treatment,the contents of AsA and GSH in the cells decreased,the contents of DHA and GSSG increased,and the activities of antioxidant enzymes SOD,CAT,APX,DHAR,MDHAR and GR in the leaves of Salix matsudana Koidz were significantly increased under Cd stress.The application of MG and NaHS increased the activities of the antioxidant enzymes CAT,GR and MDHAR,thereby alleviating the oxidative stress of cadmium on Salix matsudana Koidz.The content of MDA in leaves of Salix matsudana Koidz increased under Cd stress.Exogenous application of MG and NaHS decreased the content of MDA in cells and slowed the degree of membrane lipid peroxidation.Cd stress increased the content of Pro and MDA in cells.When applied for 40 days,exogenous application of MG and NaHS increased the intracellular Pro content.Under the condition of cadmium stress,the expression levels of SOD,CAT,APX and GR were significantly up-regulated.Under cadmium stress,exogenous application of NaHS up-regulated the expression of CAT and APX.Exogenous application of MG increased the expression level of GR and SOD compared with Cd treatment.Under cadmium stress,the expressions of genes related to metal chelation mechanism including MTs,PCS and ABCB were significantly up-regulated under cadmium stress.Exogenous application of MG up-regulated MT1A under cadmium stress,and external application of NaHS under Cd stressIncreased the expression level of MT1A and PCS Compared with Cd.Exogenous application of MG and NaHS under Cd stress significantly increased the expression levels of MT1A,MT2A,MT2B and ABCB compared with Cd treatment group.In summary,Cd stress increased intracellular ROS levels,MDA,Pro content,and increased antioxidant enzyme activity.Exogenous application of MG and NaHS under Cd treatment increased the activity of antioxidant enzymes in cells to eliminate intracellular ROS,reduce the degree of membrane peroxidation in cells,and Decreased oxidative stress.The expression levels of SOD,CAT,APX and GR in cells were significantly up-regulated under cadmium stress.Exogenous application of MG and NaHS up-regulated the expression of antioxidant enzyme gene.The gene expression levels of intracellular MTs,PCS and ABCB were up-regulated under Cd stress,which alleviate the stress of heavy metals.